With the gradual popularization of the personal computer, the liquid display technique enjoys a rapid development. Wide visual angle, low energy cost and rapid speed of response become important parameters of the liquid crystal display appliances. Among the factors determining the speed of response of a liquid crystal, in addition to the property of the crystal molecule itself, one important external factor is its orientation on the array panel. By selecting a suitable alignment film material and orientation technique to optimize the arrangement and the pretilt angle of the liquid molecule on the array substrate, the speed of response of the liquid display panel can be improved, and the visual angle of the liquid crystal display can be expanded.
Currently, depending on different types of liquid display panels, there are different modes for realizing orientation of liquid crystal. There are two common modes of orientation of liquid crystal. One is the parallel orientation mode of liquid crystal, in which an alignment film material polyimide (PI) is coated onto the surface of an array substrate to form an alignment film, followed by generation of narrow scratches on the alignment film by rubbing to induce the long axis of the liquid crystal molecules to arrange parallel to the array substrate. The other is the vertical orientation mode of liquid crystal; in this mode of orientation, siloxane is used as a vertical alignment film material, and the surface of the array substrate is treated to allow the siloxane adhere to the substrate through chemical linkages, wherein the terminal flexible chain group of the siloxane can induce the long axis of the liquid crystal molecules to arrange vertical to the substrate. At the positions close to the siloxane, the liquid crystal molecules are subject to a great orientation effect, and the long axis of the liquid crystal can be arranged vertical to the array substrate. However, at the positions farther from the siloxane, the liquid crystal molecules are subject to a limited orientation effect and the orientation is primarily subject to the induction of the oriented crystal liquid molecules. This causes deviations in the vertical direction among the liquid crystal molecules at different positions within the liquid display panel, resulting in non-uniformity of the arrangement of the entire crystal liquid in the vertical direction, which causes light scattering when light passes through the whole liquid crystal panel, thereby affecting display performance of the liquid display panel.